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The Impregnable Fortress (Azure Moon)

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The Impregnable Fortress

Cg fe16 blue sea moon mural part 2.png
Mural used to introduce The Impregnable Fortress.


Garreg Mach Monastery


Death Knight

You are finally here... Will death's scythe claim you... Or will I fall to that sword of yours... And Mercedes... Here you are as well...
— Death Knight

The Impregnable Fortress (Japanese: 鉄壁の要塞 Iron-walled fortress) is the twentieth chapter of Fire Emblem: Three Houses in the Azure Moon route.


Main article: The Impregnable Fortress (Azure Moon)/Script

As the Faerghus and Leicester forces consolidate, Dimitri declares that the group's next objective is to seize Fort Merceus, the last great hurdle between them and Enbarr, from the Death Knight. If the group discovered the Death Knight's true identity, Mercedes laments their upcoming conflict with her half-brother, but resolves to fight for what she believes in. Adrestia and Faerghus engage in battle, the Kingdom conquers Fort Merceus, and the Death Knight is slain; if his identity was discovered, he dies in a heartbroken Mercedes' arms. A soldier delivers a missive from Margrave Gautier revealing that order has been restored to Faerghus and that Kingdom reinforcements are on the way, and also reveals that a man claiming to have been involved in the Tragedy of Duscur was arrested.

Calendar - Blue Sea Moon

Blue Sea Moon
Monday Tuesday Wednesday Thursday Friday Saturday Sunday
Caspar's Birthday  
2 3 4
Story Event  
Free Day  
Fistfuls of Fish  
7 8 9
Balthus's Birthday  
10 11 12
Free Day  
Saint Cethleann Day  
Flayn's Birthday  
Rare Monster Sighting  
Morale Meals  
14 15 16 17 18 19
Free Day  
Fish of Mystery  
21 22 23 24 25 26
Free Day  
Goddess's Rite of Rebirth  
Rare Monster Sighting  
Hunting Festival  
27 28 29 30 31
Attack Fort Merceus  

Character data

New Units


Returning Characters


Item data

This section has been marked as a stub. Please help improve the page by adding information.

Name Obtainment Method
  Master Seal Tournament prize
  Brave Axe Dropped by Caspar*/enemy War Master* in Taking Fort Merceus
  Elixir Steal from Caspar*/enemy War Master*
  Elixir Steal from Linhardt*/enemy Bishop*
  Vulnerary Steal from Linhardt*/enemy Bishop*
  Extra Large Bullion Northeastern chest in Taking Fort Merceus
  Black Pearl Southerneastern chest in Taking Fort Merceus


Main article: The Impregnable Fortress (Azure Moon)/Taking Fort Merceus

You received Failnaught at the end of the previous chapter. This weapon works best on Felix, Yuri, or Anna; of the other Crest-bearing archers, Bernadetta primarily uses bows for Encloser utility while Mercedes and Hanneman have magic-oriented stat spreads.

Etymology and other languages

Names, etymology and in other regions
Language Name Definition, etymology and notes

The Impregnable Fortress




Iron-walled fortress


La fortaleza inexpugnable

The impregnable fortress


La forteresse inexpugnable

The impregnable fortress


Die uneinnehmbare Festung

The impregnable Fortress


La fortezza inespugnabile

The impregnable fortress


철벽의 요새

Iron-walled fortress

Simplified Chinese


Impenetrable fortress; lit. "fortress with walls like iron"

Traditional Chinese


Impenetrable fortress; lit. "fortress with walls like iron"


This section has been marked as a stub. Please help improve the page by adding information.


The Golden Deer's Plea The Impregnable Fortress Our Chosen Paths
Fire Emblem: Three Houses
Playable characters Black Eagles BernadettaCasparDorotheaEdelgardFerdinandHubertLinhardtPetra
Blue Lions AnnetteAsheDedueDimitriFelixIngridMercedesSylvain
Golden Deer ClaudeHildaIgnatzLeonieLorenzLysitheaMarianneRaphael
Other AloisAnna*BylethCatherineCyrilFlaynGilbertHannemanJeritza*ManuelaSetethShamir
Ashen Wolves* BalthusConstanceHapiYuri
Non-playable characters Abysskeeper*Duke AegirDuke GerthFlecheGatekeeperGlennHolstIonius IXJeraltJudithLadislavaLambertLord ArundelMonicaNaderPatriciaRandolphRheaRodrigueRufusSeirosSitriSothisTomasTiana
Bosses AcheronAelfric*AloisBaron Ochs*BiasBlaiddydCasparCatherineCharonChilonClaudeCorneliaDaphnelDedueDeath KnightDimitriDominicEdelgardFelixFerdinandFlame EmperorFlaynFraldariusGautierGloucesterGonerilGwendalHubertIngridThe Immaculate OneThe ImmovableJudithKostasKronyaLadislavaLamineLinhardtLonatoLord ArundelLorenzMercedesMetodeyMiklanMysonNaderNemesisOdessePallardóPittacusRandolphRheaRieganRodrigueSetethShamirSolonSylvainThalesWandering BeastThe Wind Caller
Personal weapons and regalia Aegis ShieldAreadbharAsclepiusAthameAxe of UkonvasaraAymrBlutgangCaduceus StaffCirce StaffCrusherFailnaughtFetters of DromiFreikugelThe InexhaustibleLance of RuinLúinOchain ShieldRafail GemScythe of SarielSeiros ShieldSpear of AssalSword of BegaltaSword of MoraltaSword of SeirosSword of the CreatorTathlum BowThunderbrandThyrsusVajra-Mushti
Chapters Part I
Prologue: An Inevitable Encounter • 1: Three Houses • 2: Familiar Scenery • 3: Mutiny in the Mist • 4: The Goddess's Rite of Rebirth • 5: Tower of Black Winds • 6: Rumors of a Reaper • 7: Field of the Eagle and Lion • 8: The Flame in the Darkness • 9: The Cause of Sorrow • 10: Where the Goddess Dwells • 11: Throne of Knowledge • 12: To War     / Outset of a Power Struggle  
Part II Silver Snow
13: Reunion at Dawn • 14: A King Without a Kingdom • 15: Valley of Torment • 16: The Rose-Colored River • 17: The Impregnable Fortress • 18: The Chaos of War • 19: Conclusion of the Crossing Roads • 20: The City Without Light • 21: Following a Dream
Azure Moon
13: Reunion at Dawn • 14: The Delusional Prince • 15: Valley of Torment • 16: The Rose-Colored River • 17: Blood of the Eagle and Lion • 18: The King's Triumphant Return • 19: The Golden Deer's Plea • 20: The Impregnable Fortress • 21: Our Chosen Paths • 22: Oath of the Dagger
Verdant Wind
13: Reunion at Dawn • 14: The Alliance Leader's Ambitions • 15: Valley of Torment • 16: The Rose-Colored River • 17: Blood of the Eagle and Lion • 18: The Golden Scheme • 19: The Chaos of War • 20: Conclusion of the Crossing Roads • 21: The City Without Light • 22: Fódlan's New Dawn
Crimson Flower
13: Beyond Escape • 14: The Master Tactician • 15: Tempest of Swords and Shields • 16: Lady of Deceit • 17: Field of Revenge • 18: To the End of a Dream
Paralogues   Part I A Cursed Relic*An Ocean ViewBlack Market Scheme*Death TollDividing the World    Falling Short of HeavenThe ForgottenLand of the Golden DeerOil and WaterRumored NuptialsThe Secret Merchant*   Sword and Shield of SeirosTales of the Red CanyonTrue ChivalryWar for the Weak  
Part II Darkness Beneath the Earth  Dividing the World    Eternal Guardian    The Face Beneath    Foreign Land and SkyForgotten HeroInsurmountable  Legend of the LakeRetribution    The Secret Merchant*  The Silver Maiden  The Sleeping Sand Legend  Weathervanes of Fódlan  
Cindered Shadows
(DLC side story)
1: The Fourth House • 2: What Lies Beneath • 3: The Rite of Rising • 4: Danger in the Dark • 5: Betrayal • 6: Return to Me • 7: Wolf Pack
Locations FódlanAbyssAdrestiaFaerghusGarreg Mach MonasteryLeicesterAlmyraBrigidDagdaSreng
Groups, objects and concepts 10 ElitesAshen WolvesBlack EaglesBlue LionsChildren of the GoddessChurch of Seiros (Knights of Seiros) • Crests (Crest Stone) • Divine PulseGolden DeerHeroes' RelicsInsurrection of the SevenMonstersThose who slither in the darkTragedy of DuscurWar of Heroes
Related topics Music LibraryName chartPre-release informationUnused content